1. Field of the Invention
The present invention relates to a method of controlling a spindle motor used in a disk drive and apparatus thereof, and more particularly, to a method of controlling starting current of an adaptive spindle motor in consideration of maximum allowable consumption power, and a disk drive using the method.
2. Description of the Related Art
A typical example of a method of controlling an adaptive spindle motor is disclosed in Korean Patent Publication No. 1998-0014310, which proposes a solution to a problem due to a voltage drop resulting from a current to be excessively consumed at an initial drive or start up of the spindle motor in a disk drive.
A disk drive utilizing a spindle motor could include a hard disk drive, a CD-ROM drive, a DVD drive, and the like. When power is supplied to the disk drive, the disk drive enters in an initial mode to drive a spindle motor to rotate a disk. The disk drive has a high power consumption at start up such that a paused disk can be started and rotated to reach a desired speed. As such, the disk drive is adapted to supply a maximum current to the spindle motor in a range of the maximum usable power.
However, the maximum usable power is restricted on the basis of maximum usable voltage, and the maximum usable current applied to the spindle motor is also restricted by the maximum usable voltage.
For example, suppose that a disk drive is adapted to utilize a single power supply of 5 V, an allowable supply voltage Vpwr of 4.75 V to 5.25 V, and a usable maximum power Pmax of 5 W, the maximum usable current is determined on the basis of the maximum allowable supply voltage of 5.25 V, the maximum usable current Imax is calculated as the following Equation 1:
                    Imax        =                              Pmax            /            Vpwr                    =                                    5              ⁢                                                          ⁢                              W                /                5.25                            ⁢                                                          ⁢              V                        =                          0.95              ⁢                                                          ⁢              A                                                          (        1        )            
A starting current of the spindle motor is determined as a result of subtracting a printed circuit board (PCB) current used in a circuit other than the spindle motor from the maximum usable current.
Even if the supply voltage Vpwr is decreased in the allowable range, the starting current of the spindle motor is restricted by the maximum usable voltage (i.e., 5.25 V). Consequently, even though more current may be used (or needed) to start the spindle motor, a fixed amount of the current is applied to the spindle motor. As a result, there is a problem in that a time required to increase the rotation speed of the spindle motor to a desired level is extended.